Menu

Show posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Show posts Menu

Messages - Camembert

#1
Tubes and Hybrids / Re: LND150 tube emulator attempt.
December 24, 2017, 05:24:15 AM
Well, I have been reading a bit about grid current and tubes and diodes, and the most shocking thing I learned is that this 'threshold' where the diode starts conducting doesn't exist! actually, it's a smooth exponential curve with a knee. Beyond the knee the diode starts to conduct 'a lot'. Before, it conducts little, but it does. Now,the grid current is in the order of microamps, so this all takes place way before the knee. And different diodes can behave differently in this region.
When I played with this in SPICE it appeared that two bav70 diodes in parallel behave very similar to a single 1N4148, wich was used in the first version of the circuit. So maybe the answer is quite simple: our KMG ran out of 1N4148 diodes and started using the parallel bav70's  as equivalent circuit..
Anyway, although I have no definite answer to my question, I learned a lot by investigating. Thank you guys for your kind replies.
#2
Tubes and Hybrids / Re: LND150 tube emulator attempt.
December 22, 2017, 09:28:59 AM
You are right about twice the current of course, but there is not a wholotta current flowing there.
I did find out that when you put two diodes in parallel, the voltage drop across the pair is slightly smaller than across a single diode. Maybe that is good for something.
But actually, I think my problem is that I don't really understand the "grid" limiter thing of wich the diodes are part...
#3
Tubes and Hybrids / Re: LND150 tube emulator attempt.
December 22, 2017, 06:37:13 AM
Hello,

Can someone explain why, in the final version of this circuit, there are two diodes in parallel between gate and source, in stead of a single one?